Something that when you go into it in a straight line you come out at a different place and/or going in a different direction than you should according to Newtonian physics. Fans are always wandering into such things in strange cities and getting losted. A slitely different affair was the turntable on which the Shirley-Savoy in Denver is mounted, so that you can start near the hotel, walk blocks and blocks, and still be near the hotel.